A composite may be described as a material produced by combining materials differing in composition or form on a macroscopic scale to obtain specific characteristics and properties. In these composites, the constituents retain their identity, can be physically identified, and often exhibit an interface between one another. For instance, a clad metal is a composite that contains two or more layers of different metal that have been bonded together. The bonding may be accomplished by co-rolling, co-extrusion, welding, diffusion bonding, casting, heavy chemical deposition, or heavy electroplating. Clad metals are commonly found on the bottoms of household pots and pans. Copper or aluminum is clad to the stainless steel pan as a way to improve the thermal conduction and de-localize heat from a burner to the entirety of the pan. For a household pan, the cladding process is usually achieved by diffusion bonding, which generally is compressing the two dissimilar metals together with high pressure at high temperatures.
While the clad arrangement described above can produce a composite with the physical properties of both metals (i.e. it is a sheet of copper bonded to a sheet of steel). In an application where a high temperature piston applies a high force normal to the copper and steel sheets, the piston would deform the low yield strength copper rather easily, regardless of the thickness of the steel sheet. While the copper is adequate for conducting the heat from the piston, it cannot handle the applied forces without deformation, particularly when at elevated temperature. Most common materials with significant thermal conductivity will either have a low melting point (like aluminum) or a low yield strength (like copper) and cannot be employed for the application of cooling a high temperature piston. While there are non-composite high thermal conductivity, high yield strength exotic materials like Copper Tungsten (CuW) which can be used for this demanding application, they are economically unfeasible for many applications.
In some instances, it is necessary or desirable to have a three dimensional composite structure that exhibits a desirable property in one dimension more than in another dimension, while the structure exhibits another desirable proper in another dimension. An example of this would be a three dimensional composite sheet that has a thermal conductivity that is higher in one direction through the sheet and has a high yield or compressive strength in another direction through the sheet.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon reading of the specification and a study of the drawings.